It is unlikely that the sound arrived before the bullet as sound travels about 300-400 meters per second. So since it looks like the two targets are moving after the bullet arrives I would be inclined to think that if the bullet did not hit either of them then whatever it did hit alerted the targets who then took cover. If the bullet actually hit either of them but was not a fatal hit, bleeding out very soon is most likely as a bullet that size will make a very large hole in the body, maybe two (entry & exit).
I didn’t say the sound got there before the bullet. I know the bullet here likely travels faster than the sound. The bullet could have been far amiss and not even in the FOV of the two and sound alerted them. I just didn’t time it from the time of the crack to them going down. Regardless, I don’t call that a kill.